package com.cw.demo.algorithm;

import java.util.*;

public class Main{
    public static void main(String[] args) throws Exception{
        Scanner sc = new Scanner(System.in);
        TreeMap<Integer, Integer> map = new TreeMap<>(); // 输出结果要求有序！
       while(sc.hasNextInt()){
            int n = sc.nextInt();
            for(int i = 0; i < n; ++i){
                int a = sc.nextInt();
                int b = sc.nextInt();
                map.put(a,map.getOrDefault(a,0) + b);
            }
       }
       for (Integer i : map.keySet()) {
           System.out.println(i + " " + map.get(i));
       }
    }
}